JP2001102979A - Mobile radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lighten the load on a base station without lowering its function and to reduce the price as a whole. SOLUTION: A modulated signal transmitted from a control station to a base station is transmitted at an intermediate frequency. A control signal component which controls the directivity of a transmission signal is superposed on a component of frequency lower than a radio frequency and converted into a light signal, which is sent. The wide-and properties of an electrical-to-optical transducer and an optical-to-electrical transducer can be reduced and the price of the electrical-to-optical transducer and optical-to-electrical transducer can be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio communication system for performing mutual communication between a mobile terminal and a control station via a base station using a radio frequency signal. Alternatively, the present invention relates to a mobile radio communication system that controls a beam to improve communication quality.

[0002]

2. Description of the Related Art As a conventional mobile radio communication system, there is, for example, a mobile radio communication system disclosed in JP-A-10-145286. FIG. 6 shows a configuration example of a mobile radio communication system shown in this conventional example.

In FIG. 6, a control signal for controlling the amplitude and phase (weighting) of each element antenna 16 is multiplexed with a modulated radio frequency signal from the control station 1 to the base station 2 and transmitted.

The base station 2 comprises an optical / electrical converter 9, a duplexer 10, a feed distribution circuit 38, a control signal distributor 11, an element antenna drive circuit 37, and element antennas 16-1 to 16-n. The splitter 10 extracts a control signal component included in the electric signal converted by the optical / electrical converter 9, and the power supply distribution circuit 38 distributes the modulated radio frequency signal.

[0005] The control signal distributor 11 distributes the weighting information of each of the element antennas 16-1 to 16-n included in the control signal and supplies them to the element antenna drive circuit 37.

The element antenna driving circuit 37 comprises a variable attenuator, a phase shifter, a frequency converter, an amplifier, and a circulator, and controls the variable attenuator and the phase shifter to set desired amplitude and phase. . Therefore, since the received signals are combined in the base station 2, it is sufficient if there is one optical transmission line for each of the uplink and the downlink between the base station 2 and the control station 1.

[0007]

However, in the mobile radio communication system shown in the prior art, the modulation signal transmitted from the control station to the base station is a radio frequency, and the directivity of the transmission signal is controlled by this. By superposing a control signal component of a lower frequency and converting it into an optical signal and sending it, it is required that the electro-optical converter and the optical / electrical converter need to have broadband characteristics.

Therefore, there is a problem that the electric / optical converter and the optical / electric converter become expensive. Also, in the base station, a variable attenuator and a phase shifter corresponding to the radio frequency signal are required to control the directivity of the transmitted signal through the variable attenuator and the phase shifter for the distributed radio frequency signal. Typically these are expensive.

In addition, there is a disadvantage that the loss increases due to distribution, amplitude control, and phase control at the radio frequency.
Further, in the conventional mobile radio communication system shown in FIG. 6, the directivity control of the antenna of the base station is performed in an analog manner (variable attenuator and phase shifter).

[0010] Therefore, it is difficult to perform such advanced beam control, and it is generally difficult to aim a null (zero point) on the interference wave. This was a big problem especially in the receiving system.

[0011]

A feature of the present invention is that a modulated signal transmitted from a control station to a base station is transmitted not at a radio frequency but at an intermediate frequency.

Accordingly, a frequency converter for converting the intermediate frequency component into a radio frequency is required in the base station, but a control signal component for controlling the directivity of the transmission signal is superimposed on a frequency component lower than the radio frequency. The optical / optical converter and the optical / electrical converter are converted to optical signals and transmitted, so that the broadband characteristics of the electrical / optical converter and the optical / electrical converter can be eased. Becomes possible.

Further, according to the present invention, in the base station, the weight for each branch for directivity control of the transmission signal is weighted from the local oscillator supplied to the intermediate frequency or a frequency converter for converting the intermediate frequency to the radio frequency. In order to control the amplitude and phase of the local signal, it is possible to reduce the cost of individual components compared to controlling the amplitude and phase through a variable attenuator and phase shifter at radio frequency. In addition, it is possible to reduce the loss.

Further, in the present invention, the modulated signal from the control station to the base station is one system, and the directivity control of the transmission signal is performed on the base station side based on the control signal transmitted to the base station.

On the other hand, a signal transmitted from the mobile terminal station to the control station via the base station is a received signal of a plurality of antennas connected to the base station or a plurality of signals synthesized from the plurality of antennas. Are transmitted to the control station by frequency multiplexing or wavelength multiplexing, and the control station performs advanced signal processing such as interference wave suppression and delayed wave synthesis. For this reason, it is easy to secure the communication quality especially in the uplink.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a mobile radio communication system according to a first embodiment of the present invention. The present embodiment is a configuration for transmitting signal transmission between the base station 2 and the control station 1 in the mobile communication system through the optical fibers 8 and 21.

The base station 2 includes n element antennas 16-1 to 16-n for transmitting and receiving radio signals to and from mobile station terminals in a radio zone (not shown), and a control station 1 through an optical fiber 8. An optical / electrical converter 9 for converting the transmitted optical signal into an electric signal, separating the electric signal converted from the optical signal into a modulation signal to the mobile station terminal and a signal for controlling the radiation directivity, and forming a desired modulation signal A variable attenuator 13 for giving amplitude and phase, a phase shifter 14, and a separation circuit 10 for outputting to a transmission beam control circuit 11 for controlling the radiation directivity of a transmission antenna, and control for controlling the transmission radiation directivity by the separation circuit 10. Receiving a signal and transmitting a control signal corresponding to this signal to the variable attenuator 13,
A transmission beam control circuit 11 for outputting to the phase shifter 14, a variable attenuator 13, a frequency conversion circuit 15 for converting a signal set to a predetermined amplitude and phase through the phase shifter 14 to a radio frequency signal, an array antenna Element antenna 1 constituting 16
3-1 to n, a frequency converter 18 for converting each of the received signals into a different frequency, a multiplexing circuit 19 for frequency multiplexing the output signals from each of the n frequency converters, and a frequency multiplexing electric signal. Electricity that performs optical modulation as a modulation signal /
A light conversion circuit 20;

In the control station 1, a signal received from the mobile station terminal via the base station 2 is converted into an electric signal by the optical / electrical converter 22 and then input to the distributor 23. In the distributor 23, the frequency-multiplexed signals are allocated to the frequency converters 24-1 to 24-n corresponding to the respective desired frequencies.

In the frequency converters 24-1 to 24-n, signals having different frequencies are frequency-converted into predetermined identical frequencies. These frequency-converted signals are each given a predetermined weight, are synthesized by a synthesizer 26, and are demodulated by a demodulator 27.

The weight determination circuit 28 determines the weight of the signal received by each of the element antennas 13-1 to 13-n based on the output signal of the demodulator 27 and outputs the signal to the weight circuits 25-1 to 25-n. Further, another output signal of the weight determination circuit 28 is input to the transmission control signal generation circuit 5, and the transmission control signal generation circuit 5 generates a transmission control signal based on the output signal of the weight determination circuit 28.

The transmission signal is obtained by frequency-converting the baseband signal from the modulator 3 by the frequency converter 4, multiplexing it with the transmission control signal by the synthesizer 6, and converting it into an optical signal by the electric / optical converter 7. Thereafter, the signal is transmitted to the base station 2 via the optical fiber 8.

In the first embodiment of the present invention, the transmission of the modulated signal from the control station 1 to the base station 2 is performed not at the radio frequency but at the intermediate frequency. Therefore, the required specifications for the optical components such as the electrical / optical converter 7 and the optical / electrical converter 9 can be reduced as compared with the case where the radio frequency is directly transmitted.

Also, a variable attenuator / phase shifter for providing a predetermined amplitude and phase can realize low loss and low cost, so that the overall price can be reduced. Also, since the transmission beam control signal is multiplexed with the transmitted intermediate frequency and transmitted, there is an advantage that the circuit configuration of the transmission system (downlink side) is simplified.

In the first embodiment of the present invention, a signal received from a mobile terminal is transmitted from the base station 2 to the control station 1 for each element antenna or beam, and the control station 1 transmits the signal for each antenna or beam. Are weighted and synthesized.

At this time, the most appropriate weighting method is to not only maximize the received power but also suppress the influence of the interference wave by directing a null (zero point) in the direction of the interference wave, or synthesize the delay wave. There is also a method for improving the SN ratio (signal-to-noise ratio).

Generally, to perform such signal processing, the signal processing circuit becomes complicated and large-scale. Therefore, by providing the function to the control station 1 that controls a plurality of base stations instead of the base station 2, the configuration of the base station 2 can be simplified and the price can be reduced.

Further, when the signal processing circuit for the received signal is provided on the control station side, for example, even if the specification of the mobile radio communication system is changed, it is sufficient to change only the control station side. System.

On the other hand, the transmitting side controls the transmitting beam in the base station 2 in an analog manner based on the control signal multiplexed from the control station to the transmitting signal. Basically, the control signal is a control signal that directs a beam toward a mobile terminal station to be communicated.

Because the radio wave is radiated with a high directivity gain toward the mobile terminal to be communicated, the reception sensitivity of the mobile terminal can be improved, and the radio wave is not radiated in unnecessary directions. This is because interference with other mobile terminals or base stations that are performing wireless communication in directions other than the mobile terminals can be reduced.

Also, this configuration is characterized in that directivity control of a transmission signal is performed in an analog manner on the base station side. For this reason, even when the specification of the mobile radio communication system is changed, for example, similarly to the reception system, the base station side device does not need to be changed, so that the system is flexible.

FIG. 2 is a diagram showing a configuration of a mobile radio communication system according to a second embodiment of the present invention. The difference between the present embodiment and the mobile radio communication system of the first embodiment of the present invention shown in FIG. 1 is that a fixed or semi-fixed between an array antenna 16 connected to the base station 2 and a transmission / reception separation circuit 17 is provided. That is, the beam forming circuit 29 is inserted.

The output signal of the beam forming circuit 29 corresponds to a beam having the maximum radiation directivity in different directions, and is generally a fixed beam forming circuit such as a Butler matrix, or a signal having a predetermined amplitude and
There is a semi-fixed phased array configuration in which the amount of phase is read from a recording medium or the like and set.

In the first embodiment, when estimating the arrival direction of the radio wave from the mobile station terminal, the relative phase difference of the received signal at each element antenna is weighted by the weighting circuits 25-1 to 25-1.
It is necessary to hold up to n.

For this reason, the frequency converters 18-1 to 18-1 to n, 2
In 4-1 to n, when converting a signal of the same frequency to a different frequency or converting a different frequency component to the same frequency, a mechanism for maintaining a relative phase difference by synchronizing is required.

However, by inserting the beam forming circuit 29 between the array antenna 16 and the transmission / reception separating circuit 17, it is possible to estimate the arrival direction of the radio wave by checking the output signal strength of the beam forming circuit 29. .

In addition, the output of the beam forming circuit can be set to m, which is smaller than the number n of element antennas, if necessary. In this case, since the number of multiplexed signals is reduced, the configurations of the base station 2 and the control station 1 can be simplified.

In addition, since the predetermined weighting of the beams having the maximum radiation directivity in different directions is equivalent to the predetermined weighting of the individual element antennas, the beam forming circuit 29 is inserted. It does not affect the transmission characteristics at all.

For this reason, in the second embodiment of the present invention shown in FIG.
6 is inserted between the transmission / reception separation circuit 17, but the present invention is not limited to this, and a similar characteristic can be obtained by inserting a beam forming circuit between the transmission / reception separation circuit 17 and the frequency converter 18.

FIG. 3 is a diagram showing a configuration of a mobile radio communication system according to a third embodiment of the present invention. The difference between this embodiment and the mobile radio communication system of the first embodiment of the present invention shown in FIG. 1 lies in the uplink system (signal from the mobile station terminal to the control station).

In FIG. 1, each of the element antennas 16-1 to 16-1
The received signal at n is converted to a different frequency in each of the frequency converters 18-1 to 18-n, frequency-multiplexed by the multiplexing circuit 19, optically modulated, and transmitted to the control station 1.

On the other hand, in FIG.
1 to n are frequency converters 18-1 to 18-n
Are converted to the same frequency. The frequency-converted signals are converted into optical signals of different wavelengths by the electric / optical conversion circuits 20-1 to 20-n, wavelength-multiplexed by the wavelength multiplexing circuit 30, and transmitted to the control station 1.

The wavelength-multiplexed and transmitted optical signal is converted into an electric signal for each predetermined wavelength component, frequency-converted, and input to a weighting circuit.

FIG. 4 is a diagram showing a configuration of a mobile radio communication system according to a fourth embodiment of the present invention. The base station 2 has the same configuration as the third embodiment of the present invention, but the configuration of the control station 1 is different from that of the first embodiment.

In the control station 1, a signal received from the mobile station terminal via the base station 2 is converted into an electric signal by the optical / electrical converter 22, and then input to the distributor 23. In the distributor 23, the frequency-multiplexed signals are allocated to the frequency converters 24-1 to 24-n corresponding to the respective desired frequencies.

The output signals of the frequency converters 24-1 to 24-n are signals that have been frequency-converted to predetermined identical frequencies. Unlike the first embodiment of the present invention, these frequency-converted signals are each converted into an analog / digital converter 32-.
The signal is converted into a digital signal by 1 to n and input to the digital signal processing circuit 33.

The digital signal input to the digital signal processing circuit 33 is digitally weighted, synthesized, and demodulated. According to this method, since analog weighting is not required, further integration is possible.

In addition to synthesizing the phases of the input digital signals and synthesizing them, by changing the algorithm of the digital signal processing unit such as interference wave suppression, arrival direction estimation, diversity, and delay wave synthesis, the base station can be further improved. Functionalization can be achieved.

Also, by changing the algorithm on the control station 1 side, it is possible to cope with various modulation methods and transmission speeds, so that the specification can be changed relatively easily.

FIG. 5 is a diagram showing a configuration of a mobile radio communication system according to a fifth embodiment of the present invention. The difference between the present embodiment and the mobile radio communication system of the fourth embodiment shown in FIG. 4 lies in the transmission beam forming structure of the base station 2.

Therefore, the control station 1 has a configuration similar to that of the fourth embodiment. In the base station 2, an optical signal modulated by a signal obtained by multiplexing a transmission beam control signal and a transmission signal from the control station 1 is transmitted.

This optical signal is converted into an electric signal by the optical / electrical converter 9 and separated into a control signal and a transmission signal by the splitter 10. The transmission beam control signal is transmitted by the transmission beam control circuit 1.
1 generates a weighting signal for each of the element antennas 16-1 to 16-n, the variable attenuators 13-1 to n, and the phase shifters 14-1 to 14-1.
n to output a control signal.

Variable attenuators 13-1 to 13-n, phase shifter 14-1
To n receive the signal from the transmission beam control circuit 11 and control the passing amplitude and phase of the signal. The difference from the fourth embodiment is that the variable attenuators 13-1 to 13-n and the phase shifters 14-1 to 14-n
Does not exist on the path of the transmission signal, but exists on the side of the local oscillation signal input to the frequency converters 15-1 to 15-n for converting the transmission signal into a radio frequency. This method is, for example, "A adaptive array for high speed wireless lo
cal loops steered by local signal phase shifters ''
As described in (IEEE AP-S International Symposium, July 1999), the bandwidth is narrower than when controlling the signal side amplitude and phase to perform amplitude and phase control on the local oscillation signal. The load on a circuit to be used is reduced, for example, the requirement for loss is not strict, and the system is low in price.

In the first to fifth embodiments of the present invention,
The input signal to the transmission control signal generation circuit 5 for determining the beam shape of the transmission signal is a signal based on the reception signal at the base station.

However, the present invention is not limited to this. For example, when the location information of the mobile station terminal is known or can be estimated on the network side connected to the control station, the network side sends the transmission control signal generation circuit 5 The transmission control signal generation circuit 5 may input the position information or information necessary for position detection, and determine the beam shape of the transmission signal from the information and the reception signal.

[0056]

As described above, according to the present invention,
A signal sent from the control station to the base station is made into one system, and the signal is used as an intermediate frequency. Further, the transmission signal is multiplexed with a control signal for a transmission beam, so that the control station and the base station can transmit the signal to the mobile station terminal. The transmission system can be simplified and downsized.

In addition, in the present invention, the received signal from the mobile station terminal is not synthesized at the base station, but the received signal at each element antenna or beam is frequency-multiplexed or wavelength-multiplexed and transmitted to the control station. The control station performs analog or digital signal processing. For this reason, compared with the case where each signal is synthesized in the base station,
It is possible to improve communication quality.

The amplitude and phase control on the transmitting side is analog-controlled by the base station, and the receiving side is controlled by the control station. In this system, for example, when there is a change in the communication system or the like, there is no change on the base station side, and it is possible to respond by changing the hardware or software on the control station side.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a hardware configuration of a base station and a control station of a mobile radio communication system according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a hardware configuration of a base station and a control station of a mobile radio communication system according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a hardware configuration of a base station and a control station of a mobile radio communication system according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a hardware configuration of a base station and a control station of a mobile radio communication system according to a fourth embodiment of the present invention.

FIG. 5 is a diagram illustrating a hardware configuration of a base station and a control station of a mobile radio communication system according to a fifth embodiment of the present invention.

FIG. 6 is a diagram showing a hardware configuration of a base station and a control station of a mobile radio communication system according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Control station 2 ... Base station 3 ... Modulator 4, 15, 18, 24 ... Frequency conversion circuit 5 ... Transmission control signal generation circuit 6, 19 ... Multiplexing circuit 7, 20: an electric / optical converter 8, 21, an optical fiber 9, 22, an optical / electric converter 10, a separation circuit 11, a transmission beam control circuit 12, 23, 34 ... Distribution circuit 13 ... Variable attenuator 14 ... Phase shifter 16 ... Array antenna 17 ... Transmission / reception separation circuit 25 ... Weighting device 26 ... Synthesizer 27 ... Demodulator 28 ... weight determination circuit 29 ... beam forming circuit 30, 31 ... wavelength multiplexing circuit 32 ... analog / digital converter 33 ... digital signal processing circuit 35 ... local oscillator 36 ... Beam control calculation unit 37 ・ ・ ・ Element antenna drive Road 38 ... feed distribution circuit

Continued on the front page F-term (reference) 5J021 AA05 AA06 CA06 DB03 EA04 FA17 FA20 FA24 FA29 FA30 FA32 HA05 HA10 5K002 AA05 CA03 CA14 DA02 DA09 GA07 5K059 CC04 DD07 DD10 5K067 CC02 CC24 DD02 EE02 EE10 EE16 EE37 GG01KK02

Claims (7)

[Claims] 1. A mobile radio communication system comprising: a control station; a plurality of base stations connected to the control station via an optical transmission line; and a mobile terminal performing radio communication with the base station. An array antenna composed of a plurality of element antennas arranged at predetermined intervals, and an optical modulation signal in which an electric signal modulated by a transmission signal transmitted from the control station and a transmission directivity control signal are multiplexed. Means for converting the converted electric signal into an electric signal modulated by a transmission signal and a directivity control signal; means for distributing the electric signal modulated by the transmission signal; Weighting means for weighting an electric signal modulated with the transmission signal based on a directivity control signal; first frequency conversion means for converting an output signal of the weighting means into a radio frequency signal; A second frequency converting means for converting the frequency of the electric signal received by each element antenna into a different frequency, a frequency multiplexing means for synthesizing the frequency-converted signal group and performing frequency multiplexing, A first electrical / optical conversion unit that performs optical modulation using the multiplexed signal as a modulation signal, wherein the control station converts the optical modulation signal from the optical transmission line into an electrical signal. Means, means for separating a frequency multiplexed signal which is an electric signal, third frequency conversion means for converting the separated frequency multiplexed signals to the same frequency, and the same frequency by the third frequency conversion means. Using the converted signal group as an input signal, each signal is optimally weighted in order to extract a desired signal component, and a signal processing unit that synthesizes a signal is radiated from the base station based on a received signal. Directivity calculation circuit for determining the directivity of a signal to be transmitted; and multiplexing means for multiplexing an electric signal modulated with information to be transmitted to the base station and a control signal for controlling the directivity of the array antenna of the base station. And performing a second optical modulation using the multiplexed signal as a modulation signal.
Mobile radio communication system characterized by comprising: 2. A mobile radio communication system comprising a control station, a plurality of base stations connected to the control station via an optical transmission line, and a mobile terminal performing radio communication with the base station. An array antenna composed of a plurality of element antennas arranged at predetermined intervals, and an optical modulation signal in which an electric signal modulated by a transmission signal transmitted from the control station and a transmission directivity control signal are multiplexed. Means for converting the converted electric signal into an electric signal modulated by a transmission signal and a directivity control signal; means for distributing the electric signal modulated by the transmission signal; Weighting means for weighting an electric signal modulated with the transmission signal based on a directivity control signal; first frequency conversion means for converting an output signal of the weighting means into a radio frequency signal; A second frequency conversion means for converting the frequency of the electric signal received by each element antenna; and a first group for performing optical modulation with optical signals of different wavelengths using the group of these frequency-converted signals as modulation signals. An optical modulating means, comprising: synthesizing means for synthesizing signals converted into optical signals of these different wavelengths, wherein the control station comprises: an optical signal separating means for separating different optical modulated signals from the optical transmission line; An optical / electrical converting unit connected to the optical signal separating unit and converting each optical modulation signal into an electric signal; and a signal group converted to the same frequency by the optical / electrical converting unit as an input signal, A signal processing unit that performs optimal weighting on each signal in order to extract a signal component and synthesizes a signal; a directivity calculation circuit that determines a directivity of a signal radiated from the base station based on a received signal; Multiplexing means for multiplexing an electric signal modulated with information to be transmitted to a base station and a control signal for controlling the directivity of the array antenna of the base station; and performing optical modulation using the multiplexed signal as a modulation signal. Second to do
Mobile radio communication system characterized by comprising: 3. A beam forming circuit according to claim 1, wherein a beam forming circuit for forming a predetermined beam is inserted between said array antenna and said weighting means or said second frequency converting means. Mobile radio communication system 4. A mobile radio communication system comprising: a control station; a plurality of base stations connected to the control station via an optical transmission line; and a mobile terminal that performs radio communication with the base station. An array antenna composed of a plurality of element antennas arranged at predetermined intervals, and an optical modulation signal in which an electric signal modulated by a transmission signal transmitted from the control station and a transmission directivity control signal are multiplexed. Means for converting the converted electric signal into an electric signal modulated by a transmission signal and a directivity control signal; distribution means for distributing the electric signal modulated by the transmission signal; First frequency conversion means connected to the distribution means for converting an electric signal modulated with a transmission signal into a radio frequency signal, and local oscillation signal generation means for supplying a local oscillation signal to the first frequency converter; Weighting means disposed between the first frequency conversion means and the local oscillation signal generating means for weighting an electric signal modulated with the transmission signal based on the directivity control signal; and receiving at each of the element antennas Second frequency converting means for converting the frequency of the converted electric signals into different frequencies, frequency multiplexing means for synthesizing the frequency-converted signal group and frequency-multiplexing the signals, and modulating the frequency-multiplexed signal with a modulated signal And a first electrical / optical converter that performs optical modulation, wherein the control station is an optical / electrical converter that converts an optical modulation signal from the optical transmission line into an electrical signal, and an electrical signal. Means for separating the frequency multiplexed signal, third frequency converting means for converting each of the separated frequency multiplexed signals to the same frequency, and conversion to the same frequency by the third frequency converting means. A signal processing unit that performs optimal weighting for each signal in order to extract a desired signal component using the converted signal group as an input signal and synthesizes a signal, and a signal processing unit that radiates from the base station based on a received signal. A directivity calculation circuit for obtaining directivity; a multiplexing unit for multiplexing an electric signal modulated with information to be transmitted to the base station and a control signal for controlling the directivity of the array antenna of the base station; A second method of performing optical modulation using a multiplexed signal as a modulation signal
Mobile radio communication system characterized by comprising: 5. A mobile radio communication system comprising: a control station; a plurality of base stations connected to the control station via an optical transmission line; and a mobile terminal performing radio communication with the base station. An array antenna composed of a plurality of element antennas arranged at predetermined intervals, and an optical modulation signal in which an electric signal modulated by a transmission signal transmitted from the control station and a transmission directivity control signal are multiplexed. Means for converting the converted electric signal into an electric signal modulated by a transmission signal and a directivity control signal; distribution means for distributing the electric signal modulated by the transmission signal; First frequency conversion means connected to the distribution means for converting an electric signal modulated by a transmission signal into a radio frequency signal; and a local oscillation signal generation means for supplying a local oscillation signal to the first frequency converter Weighting means disposed between the first frequency conversion means and the local oscillation signal generating means for weighting an electric signal modulated with the transmission signal based on the directivity control signal; and A second frequency converter for frequency-converting the received electric signal, a first optical modulator for optically modulating each of these frequency-converted signals as a modulation signal with optical signals having different wavelengths, A synthesizing unit for synthesizing the signals converted into the optical signals having the different wavelengths, wherein the control station separates the optical modulation signals from the optical transmission line, and the optical signal separating unit. Means for converting each optical modulation signal into an electrical signal, and a signal group converted into the same frequency by the optical / electrical conversion means as an input signal. A signal processing unit that performs optimal weighting on each signal to extract components and synthesizes signals; a directivity calculation circuit that obtains directivity of a signal radiated from the base station based on a received signal; Multiplexing means for multiplexing an electric signal modulated with information to be transmitted to the base station and a control signal for controlling the directivity of the array antenna of the base station, and performing a light modulation using the multiplexed signal as a modulation signal. 2
Mobile radio communication system characterized by comprising: 6. A beam forming circuit according to claim 4, wherein a beam forming circuit for forming a predetermined beam is inserted between said array antenna and said weighting means or said second frequency converting means. Mobile radio communication system 7. A signal processing unit which is provided in the control station and performs optimal weighting on each signal to extract a desired signal component by using a signal group converted into the same frequency as an input signal and synthesizes the signals. Has an analog / digital conversion function, converts an input signal to the signal processing unit into a digital signal, weights each input signal, and synthesizes a signal. Mobile radio communication system as described